Information

5.7.5 LPTMR clocking
The prescaler and glitch filters in each of the LPTMRx modules can be clocked as shown
in the following figure.
NOTE
The chosen clock must remain enabled if the LPTMRx is to
continue operating in all required low-power modes.
LPTMRx_PSR[PCS]
LPTMRx prescaler/glitch
filter clock
MCGIRCLK
OSCERCLK
ERCLK32K
LPO
Figure 5-5. LPTMRx prescaler/glitch filter clock generation
5.7.6 USB FS OTG Controller clocking
The USB FS OTG controller is a bus master attached to the crossbar switch. As such, its
clock is connected to the system clock.
NOTE
For the USB FS OTG controller to operate, the minimum
system clock frequency is 20 MHz.
The USB OTG controller also requires a 48 MHz clock. The clock source options are
shown below.
USB 48MHz
USB_CLKIN
MCGPLLCLK or
MCGFLLCLK
SIM_CLKDIV2
[USBFRAC, USBDIV]
SIM_SOPT2[USBSRC]
Figure 5-6. USB 48 MHz clock source
Module clocks
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
172
Preliminary
Freescale Semiconductor, Inc.
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